ABSTRACT: PROJECT 2 (P2) Background: Evidence is lacking to guide regulatory strategies to reduce the prevalence of vaping among never-smokers without discouraging smokers from switching to what may be a lower harm product in e-ciga- rettes. Vape shops, which specialize in selling a variety of e-cigarette products, are a key channel of exposure; and their customers may be highly impacted by changes in FDA product regulation or fixed marketing standards. P2 aims to provide the FDA with evidence regarding how different segments of the e-cigarette-using vape shop customer population would likely react to new regulatory standards on e-cigarette products. P2 will contrast three groups of vape shop customers?e-only users (who never smoked cigarettes extensively); switchers (who quit smoking and now only use e-products); and dual users (who currently use both e-cigarettes and cigarettes)? regarding their perceived future appeal, and anticipated purchasing and use of e-cigarette products, as well as perceived future appeal, purchase and use of combustible products after hypothetical regulatory changes. Method: Intercept interviews with 720 customers exiting 30 vape shops in each of four neighborhoods; African American, Hispanic/Latino, Asian Pacific Islander-Korean, and Non-Hispanic White. Aim 1. To test the hypoth- esis that hypothetical product characteristics regulation on sweet flavors, propylene glycol / vegetable glycerin ratio in e-liquids, that produce thick vapor clouds, and ability to calibrate a device, will be associated with lower product appeal, and anticipated future purchasing and use of e-cigarettes in e-only users (vs. switchers and dual users). Aim 2. To test the hypothesis that hypothetical fixed marketing standards eliminating e-cigarette price deals, colorful print advertisements/posters, and product sampling, will be associated with lower product appeal, and anticipated purchasing and use of e-cigarettes in e-only users (vs. switchers and dual users). Aim 3. To test the hypothesis that these same hypothetical product regulations and fixed marketing standards will be associated with lower product appeal, and anticipated purchasing and use of e-cigarettes on young adults (age 21-29) vs. middle/older adults (30+). Aim 4. To examine the above associations as a function of a) consumer current specific product(s) used, b) race/ethnicity, c) consumer?s gender, d) SES, and e) shop neighborhood ethnic location. For each aim, we will explore group differences in whether e-product characteristic regulation and fixed marketing standards impact product appeal, and anticipated purchase and use of combustible prod- ucts. Integration with ?Intersections of Products with Populations? theme: P2 will study a variety of do- mains of e-cigarette product diversity that overlap with and complement domains studied in other USC-TCORS projects. In addition to contrasting populations by vaping status, P2 uniquely captures population diversity in multiple socio-demographic and user characteristics. FDA Scientific domains addressed: Behavior and Mar- keting.